Over 600,000 users were used as guinea pigs without
their consent, which raises a number of serious ethical and legal
questions (particularly due to the fact that this study received federal
funding), however there is an even more disturbing angle to this story.It turns out that this research was connected to a Department of Defense project called the Minerva Initiative, which funds universities to model the dynamics, risks and tipping points for large-scale civil unrest across the world.

In the official credits for the study conducted by Facebook you'll find Jeffrey T. Hancock from Cornell University. If you go to the Minerva initiative website you'll find that Jeffery Hancock received funding from the Department of Defense for a study called "Cornell: Modeling Discourse and Social Dynamics in Authoritarian Regimes". If you go to the project site for that study you'll find a visualization program that models the spread of beliefs and disease.

Cornell University is currently being funded for another DoD study right now called "Cornell: Tracking Critical-Mass Outbreaks in Social Contagions" (you'll find the description for this project on the Minerva Initiative's funding page).

The Department of Defense's investment in the mechanics of
psychological contagion and Facebook's assistance, have some very
serious implications, particularly when placed in context with other
scandals which have broken in the past two years.

The U.S. government hasn't sought these capabilities for the sake of science. We know from the Cuban Twitter scandal,
where the U.S. State Department where got caught red handed attempting
to topple the Cuban government through social media, that these
capabilities are already being used for offensive operations. Combine
that with the fact that the U.S. Military got exposed in 2011
for developing 'sock puppet' software to create fake online identities
and spread propaganda and an ominous picture snaps into focus.

The U.S. government is militarizing social media through a
combination of technology and social sciences, and Facebook is helping
them.